Quite often some additives are added into soils to improve the stability of material. The method of stabilization is named after the name of additive being used in the soil to improve its characteristics. For example cement stabilization.
The method of cement stabilization is usually used in the construction of the roads in order to improve the stability of the sub grade. Cement is very important component in stabilizing the soil during the construction of roads; the soil which can be economically pulverized is usually stabilized with cement. Well graded sand gravel mixtures are one of the best soils for the cement stabilization method. With at least 10%of the material passing # 200 sieve, with a coefficient of uniformity value < or = to 5. Some of the precaution must be made while applying cement stabilization technique. The soil which is under consideration should not contain sulphates or organic materials, these two elements make the soil unsuitable for the cement stabilization method.
Usually practice is done to determine the contents of cement for a stable mixture on the basis of their strengths. In the construction of road and bridges the minimum strength required is 3.5 N/ mm2.
Methods used in soil cement construction:
There are two main methods used in soil-cement construction.
- Central plant method.
- Mix-in-place method.
Central plant method:
Central plant method is a constructional method in which specific proportions of soil and cement are mixed with each other and then dried to obtain a uniform color. When a dried mixture is obtained it is then remixed by adding water in it, the material thus performed is thoroughly remixed, and then used on the formations which are made ready for spreading and compaction. The plants using this method require a large place and the projects are usually expensive this method is used on those places where long interrupted runs are required. But the advantage of this method is that it provides us better control on the quality and gives fast construction.
You might have encountered many agricultural rotators cultivators which are similar to multi pass machinery. In this process by mixing the soil it is first pulverized and according to the requirement of the final chamber it is shaped with the help of blade graders. After that soil is mixed with cement by spreading the cement over the surface and allows it to dry to uniform color. This process is performed in no. of stages, in each stage water is added and soil and cement are remixed, this makes cement and soil mixed with each other properly. After passing the mixture through a no. of stages, when the moisture content s of our requirements is achieved, the new soil produced is reshaped with the help of graders, and after it, compacted using rollers. The plants using mix-in-place method do not require a large place they are usually small and light and thus can be used in confined spaces.